1. Field of the Invention
This invention relates generally to the field of secure housing arrangements for enclosing electronic circuitry or the like, and more particularly this invention relates to low cost housings requiring no tools to assemble yet requiring tools to disassemble.
2. Background of the Invention
It is frequently desirable to provide an enclosure or housing for an electronic apparatus which has a degree of tamper resistance built in by requiring that a tool be used to disassemble the housing. This makes access to possibly hazardous voltages within the housing more difficult thus, enhancing the safety of the electronic device and reducing the hazard of shock or fire.
In fact, product safety organizations such as Canadian Standards Association (CSA) and Underwriter Laboratories (UL) have established standard for such enclosures. CSA Standard for Data Processing Equipment for Consumer and Commercial Products C22.2 No. 154-M1983 and UL 478 Standard for Information-Processing and Business Equipment are two such standards for so called "secure enclosures". It is advantages for both safety and business considerations to enclose electronic devices inside of housings which meet these types of specifications.
Several examples of fastening arrangements which are typically used to satisfy the requirements of such standards are ordinary screw fastener arrangements or quarter-turn coin operated fasteners. Unfortunately, there are serious cost drawbacks to utilizing either of these common fastening arrangements. In the case of screw fasteners, although the part cost is nominal the labor associated with assembling a screw assembled enclosure is considerable. In the case of quarter-turn coin operated fasteners, parts cost is relatively higher and the degree of security attained is somewhat limited due to the many types of devices (including coins) which can be used to open such fasteners. Additionally, serious damage to electronic circuits may occur if such metal fasteners are accidentally dropped or left inside such housings.
Resilient latches of various arrangements have been used for assembling various types of plastic containers in the past. However, the present invention utilizes a resilient plastic latching arrangement which allows for inexpensive ABS type plastic to be used abundantly and provides a secure enclosure of exceedingly low parts and labor costs. In addition, the recessed face plate arrangement of the present invention provides an added measure of tamper resistance.